regarding textures, i even noticed a difference in the Elemental Cinematic Part 1 demo (the GTX 680 one).
Just look at the following press screenshot that was released alongside the 911 MB 1080p video:
Now compare this press screenshot with the same scene (same frame) in the 911 MB 1080p video available over there for example:
The texture quality, and apparently the lighting as well, appear to be much better in the press screenshot as compared to in the video
(see the wall textures next to the archway for example).
Also, in the press screenshots released alongside the video there are another two pictures which show a difference.
One of the press screenshots shows how it looks like in the 911 MB 1080p video (apart from the rendering resolution/supersampling):
While another press screenshot shows how it is not
looking in the 911 MB 1080p video:
The lighting in the second picture is different than in the first picture / different than in the 911 MB 1080p video.